Coil arrangement for high frequency purposes



H. VOGT Feb. 29, 1944.

COIL ARRANGEMENT FOR HIGH FREQUENCY PURPOSES Original Filed July 11, 1935 Patented Feb. 29, 1944 COIL ARRANGEMENT FOR HIGH FREQUENCY PURPOSES Hans Vogt, Berlin-Neukolln, Germany, assignor to Ferrocart Co p ration of America, Hastings on Hudson, N. Y., a corporation of Delaware Continuation of application Serial No. 30,906, July 11, 1935. This application August 30, 1940, Serial No. 354,889. In Germany July 14, 1934 6 Claims.

The high frequency coils with magnetic core that have in recent times been much used, particularly in the wireless receiving set industry, have as a rule previously been made in. the following way: the winding was secured to the magnetic core in some way, while the latter was for its part fitted in a special holder. The present innovation makes possible considerable simpliflcation of this manufacturing process, considerable economy both of material and labor being achieved, while the process can be carried out with less waste. In accordance with this new process, an insulating body is used as a holder, which holds not only the winding or windings but also the magnetic core or cores themselves; This arrangement is used in particular with great advantage for the purpose of uniting, in the simplest possible way, several coils and magnetic cores to form one constructional whole, one single insulating holder being used, by means of which holder all the windings and magnetic cores are held.

The insulating holder body possesses a footlike attachment which serves to secure the whole to the base-plate. This foot-plate serves at the same time as a holder for soldering lugs.

A few examples of execution of this innovation will now be described in detail with the aid of the accompanying drawing, in which:

Fig. l is a longitudinal sectional view through a transformer embodying the invention;

Fig. 1a is a fragmentary perspective view, on a larger scale, of the mounting tube and the parts for eflecting a trimming adjustment of the inductance of a coil;

Figs. 2a and 2b are longitudinal sectional views, at right angles to each other, through another embodiment of the invention; and

Fig. 2c is a plan view of the same but with the shield can removed.

Fig. 1 shows a very simple form of realization of the innovation. The insulating body serving as a holder consists of a tube I, preferably round, which, for the P pose of avoiding high frequency losses, is made for preference of insulating materials giving small losses, for example ceramic products of crystalline structure, thermoplastic molding resins of the polystyrol type or molding mixtures of such resins which can be die-cast, or mixtures of polystyrol and quartz, mica, ceramie powders, and the like. Inside this insulating tube I are fitted the bar-shaped magnetic cores 2 and 3, which can either be jammed in tight or secured by means of an adhesive. Around the periphery of the insulating tube I are fitted the windings 4 and 5, which are preferably wound so as to be self-supporting, in which case they can simply be pushed on to the tube I, or elsethe wire can be wound directly on to the tube I. According to circumstances, there is also the possibility of closing completely or almost completely the magnetic circuit by means of further magnetic bodies i and I, pushed on to the insulating tube, which magnetic bodies can be made in the shape of plates or bowls. The arrangement oifers the advantage that all parts are able to be moved along the axis, so that both the magnetic core in the coil and the magnetic bodies on the outside, or the whole system, can be moved along the insulating tube I, with the object of altering the self-induction or the coupling factor. Special coupling windings can be added on the tube I.

In many cases, it is desirable for it to be possible to effect this axial displacement not only by hand, but also by means of an appliance, if possible from outside through a hole in the shield cup 8, which encloses thewhole arrangement. Such an operation can be carried out advantageously by means of a very simple device also depicted in Fig. 1 and shown in greater detail in Fig. 1a of the plan. As can be seen, the adjustment is effected by means of a rod 8 which may be inserted in a slot III in the insulating tube II, the rod having a fairly snug fit in the slot and terminating in an eccentrically positioned pin Ii which enters a small hole in the magnetic core 2. Rotation of the rod 8 thus eflects an adjustment of the magnetic core longitudinally of the insulating tube II and the winding I mounted thereon. By turning the pin 8, the magnetic core I 2 is moved to-and-fro and very sensitive adjustment is made possible. The same regulating device can be used with small alterations for the purpose of moving to-and-iro the other coil parts.

At the bottom, a base-plate II, also of insulating material giving small losses, is attached to the insulating tube I, or else this base-plate can be made in one piece with the insulating tube. This base-plate I2 serves for fastening the whole arrangement on the chassis, for holding the insulating tube and acts as a holder for the soldering lugs and is also used for fastening the shield cup.

Figs. 2a, b and c show a rather difierent, particularly advantageous arrangement. The cores consist in this case of an E-shaped part II and a straight magnet yoke I3. The insulating support I5 is also in the form of a tube, but it is fitted-with cavities and projections to enable the insertion of the E-pieces and the yokes and hold clearly in Fig. 2b in which the lower coil is shown in section so that the magnetic core and the I coil frame are visible. Here again the base-plate I1 is provided at the bottom, preferably cast at the same time as the support, this base-plate serving to hold and secure the soldering lugs l8 and also to fasten the shield cup IS. The fix ing screws 2|, with the aid of which' the shield v downwards and serve at the same time for fascup I5 andthe base-plate H. are secured, extend tening the whole arrangement on the base-board. The arrangement described above is distinguished by particularly handsome and simple construction with small consumption of material, involving little work and avoiding waste of ,construction.

. Such a coil arrangement is used with advantage as a set of coils for several wavebands,'for example, short, medium and long waves, and also as band filters, for example high frequency band filters orv medium frequency band filters. By

'altering, the distanc between the individual coils or by inserting a metal diaphragm 20 or a magnetic body between the coils, the coupling can be changed. I Y

Instead of making the insulating support in the shape of a tube with co-axially mounted coils, this insulating body can of course (as it can be given without difficulty more complicated shapes during the molding) be formed in such a way that the-axes lie parallel to one another-or at right-angles to one another in order to attain a less close coupling, or the like.

This application is a continuation of, and filed as a substitute for, my copending application Serial Number 30,906, filed July 11, 1935.

I claim: 1. A coil assembly, comprising a cylindrical tubular insulating member of thin uniform wall thickness, a plurality of axially spaced cylindrical corepieces tightly fitting the inside of said tubular member, a low capacity multi-layer winding for each core piece, arranged tightly on said tubular member substantially symmetrical to its associated core piece, a core piece extending exteriorly of each of said windings, and means at one end of said tubular member for securing the coil assembly to a support.

2. A coil assembly for use at radio frequencies, said assembly comprisinga plurality of low capacity multi-layer coils, magnetic cores substantially completely enclosing the respective coils, and insulating means for supporting said cores and coils in spaced relation, said insulating means having means at one end thereof for securing the coil assembly to a support.

3. A coil assembly as claimed in claim 2, wherein one or said magnetic cores comprises a plu-' rality of relatively adjustable core sections, whereb the self-inductance of the coil within that core may be adjusted.

4. A coil assembly for use at radio frequencies, said assembly comprising a thin-walled tubular ,member of insulatin material, a plurality of low capacity multiple layer coils fitted upon said tubular member and axially spaced from each other, and magnetic cores substantially completely enclosing the respective coils, each of said cores comprising a cylindrical core section tightly fitted'into said tubular member and core sections fitted upon the exterior of said tubular member to extend radially along the sides of tral core section of each core axially of said pair of core sections of that core.

- HANS VOGT. 

